Re:_[MITgcm-support]_Advection_schemes

[Petter Stenström]

Samar and Martin,

thanks for your suggestions. I'm not using pkg/ptracers, but only tr1 which
is available with ALLOW_PASSIVE_TRACER defined. It seems like a good idea
to use the package instead. I'll try that. (And yes, "if (multidimadv" is
indeed commented).

The results that I described were with T as a passive tracer (talpha=0).
tr1 uses kappaRT, so that's why I thought T and tr1 should stay identical
if initialized identically. 

/Petter

------- Original message -------
From: mlosch at awi-bremerhaven.de
Date: Thu, 19 Aug 2004 08:19:45 +0200

Petter,
I am a little puzzled by your results, I have been using DST-3 with 
flux limiter (scheme 33) for quite some time now also with older 
checkpoints and (17) passive tracers (with the ptracers-pkg), and I 
haven't had any of your problems, yet. Let's not hope that you have 
discovered something that will make my last year's work worthless 
(don't worry, it's worthless anyway (o:)

Another test: use a linear equation of state (eosType='LINEAR') and set 
sBeta=0., so that theta is basically density/buoyancy and salinity is 
passive. Then salinity and your explicit passive tracer should give the 
same results (provided that ptracers_forcing uses the salinity forcing, 
this is the default). In all of my experiments this was the case.

Martin

On Aug 19, 2004, at 12:20 AM, Petter Stenström wrote:

> Hi Patrick,
>
> Thanks for your reply. Noop, I did not forget to specify
> tracerAdvScheme=33. The problem seems rather to be that multiDimAdv 
> has to
> be false when using scheme no 33. I looked again in the documentation 
> and
> found a note on that.
>
> The strange thing is that this seems to be required only for tr1, not 
> for T
> and S. I ran a simple experiment in a simple domain with exactly the 
> same
> initial distribution and concentration of T and tr1, and the same 
> advection
> scheme (33). tr1 goes to infinity, whereas T stays on realistic values.
> Strange since tr1 seems to use the same diffusivity constants as T in 
> the
> default configuration. I will look closer in the code and try to 
> figure out
> what the difference between the two is.There are slight differences 
> also
> when using other schemes (I've tried 3rd order upwind biased).
>
> /Petter
>
>
>
> ------- Original message -------
> From: heimbach at MIT.EDU
> Date: Wed, 18 Aug 2004 15:27:19 -0400
>
> Hi Petter,
>
> sorry I oversaw your reply
> (I am CC-ing to mitgcm-support and suggest
> that you always send to that list).
>
> Re. your question I think you forgot to also specify
>  tracerAdvScheme = 33
> in your data file.
> Can you try and see whether that gives the
> desired results?
>
> -Patrick
>
>
>
> Quoting Petter StenstrXm <petters at kth.se>:
>
>> Hi Patrick,
>>
>> thanks. 33 is apparently a flux limited 3rd order DST. It works fine 
>> with
> S
>> and T, but not with a passive tracer. I cannot understand why, but 
>> false
>> extrema appear in the TR1 field, but not in the S and T fields, when 
>> I use
>> 33 for all of them. Is there an obvious explanation for this that I 
>> don't
>> see?
>>
>> Petter
>>
>> ------- Original message -------
>> From: heimbach at MIT.EDU
>> Date: Tue, 17 Aug 2004 14:35:19 -0400
>>
>> Hi Petter,
>>
>> they are described in sections 2.16, 2.17
>> http://mitgcm.org/sealion/online_documents/node71.html
>> http://mitgcm.org/sealion/online_documents/node76.html
>> of the online documentation,
>> but for the actual number associated with each sheme
>> you'll have to look in the header file
>> pkg/generic_advdiff/GAD.h
>>
>> -Patrick
>>
>>
>>
>> Quoting Petter StenstrXm <petters at kth.se>:
>>
>>> Hi!
>>>
>>> Is there a list of all the different advection schemes available and
> their
>>> corresponding numbers? I cannot find any in the documentation.
>>>
>>> I have been using advection scheme 33 for some time (which I thought
> was a
>>> flux limiter scheme), but when I look now, I cannot see that the 
>>> value
> 33
>>> is interpreted anywhere in the code.
>>>
>>> Regards,
>>>
>>> Petter Stenström
>>> Dept of Land and Water Res Eng
>>> Royal Institute of Technology
>>> SE-100 44 Stockholm
>>> Phone: +46 8 7908657
>>> Email: petters at kth.se
>>>
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
>>>
>>
>>
>> --------------------------------------------------------
>> Patrick Heimbach   Massachusetts Institute of Technology
>> FON: +1/617/253-5259                  EAPS, Room 54-1518
>> FAX: +1/617/253-4464             77 Massachusetts Avenue
>> mailto:heimbach at mit.edu               Cambridge MA 02139
>> http://www.mit.edu/~heimbach/                        USA
>>
>>
>>
>>
>
>
> --------------------------------------------------------
> Patrick Heimbach   Massachusetts Institute of Technology
> FON: +1/617/253-5259                  EAPS, Room 54-1518
> FAX: +1/617/253-4464             77 Massachusetts Avenue
> mailto:heimbach at mit.edu               Cambridge MA 02139
> http://www.mit.edu/~heimbach/                        USA
>
>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://dev.mitgcm.org/mailman/listinfo/mitgcm-support


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